WASHINGTON — In the middle of an intense political fight about the program that shields from deportation young immigrants who were brought illegally to the United States as children, a federal judge in California issued a nationwide injunction late Tuesday ordering the Trump administration to start the program back up again.

Saying the decision to kill it was improper, Judge William Alsup of Federal District Court in San Francisco wrote that the administration must “maintain the DACA program on a nationwide basis” as the legal challenge to the president’s decision goes forward.